Paracetamol/acetaminophen (single administration) for perineal pain in the early postpartum period.

BACKGROUND

Perineal pain is a common but poorly studied adverse outcome following childbirth. Pain may result from perineal trauma due to bruising, spontaneous tears, surgical incisions (episiotomies), or in association with operative vaginal births (ventouse or forceps-assisted births). This is an update of a review last published in 2013.

OBJECTIVES

To determine the efficacy of a single administration of paracetamol (acetaminophen) used in the relief of acute postpartum perineal pain.

SEARCH METHODS

For this update, we searched the Cochrane Pregnancy and Childbirth's Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (9 December 2019), and reference lists of retrieved studies.

SELECTION CRITERIA

Randomised controlled trials (RCTs), including cluster-RCTs, comparing paracetamol to placebo. We excluded quasi-RCTs and cross-over trials. Data from abstracts would be included only if authors had confirmed in writing that the data to be included in the review had come from the final analysis and would not change.

DATA COLLECTION AND ANALYSIS

Two review authors assessed each study for inclusion and extracted data. One review author reviewed the decisions and confirmed calculations for pain relief scores. We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

This update identified no new trials so the results remain unchanged. However, by applying the GRADE assessment of the evidence, the interpretation of main results differed from previous version of this review. We identified 10 studies involving 2044 women, but all these studies involved either three or four groups, looking at differing drugs or doses. We have only included the 1301 women who were in the paracetamol versus placebo arms of the studies. Of these, five studies (482 women) assessed 500 mg to 650 mg and six studies (797 women) assessed 1000 mg of paracetamol. One study assessed 650 mg and 1000 mg compared with placebo and contributed to both comparisons. We used a random-effects meta-analysis because of the clinical variability among studies. Studies were from the 1970s to the early 1990s, and there was insufficient information to assess the risk of bias adequately, hence the findings need to be interpreted within this context. The certainty of the evidence for the two primary outcomes on which data were available was assessed as low, downgraded for overall unclear risk of bias and for heterogeneity (I² statistic 60% or greater). More women may experience pain relief with paracetamol compared with placebo (average risk ratio (RR) 2.14, 95% confidence interval (CI) 1.59 to 2.89; 10 trials, 1279 women), and fewer women may need additional pain relief with paracetamol compared with placebo (average RR 0.34, 95% CI 0.21 to 0.55; 8 trials, 1132 women). However, the certainty of the evidence was low, downgraded for unclear overall risk of bias and substantial heterogeneity. One study used the higher dose of paracetamol (1000 mg) and reported maternal drug adverse effects. There may be little or no difference in the incidence of nausea (average RR 0.18, 95% CI 0.01 to 3.66; 1 trial, 232 women; low-certainty evidence), or sleepiness (average RR 0.89, 95% CI 0.18 to 4.30; 1 trial, 232 women; low-certainty evidence). No other maternal adverse events were reported. None of the studies assessed neonatal drug adverse effects.

AUTHORS' CONCLUSIONS: A single dose of paracetamol may improve perineal pain relief following vaginal birth, and may reduce the need for additional pain relief. Potential adverse effects for both women and neonates were not appropriately assessed. Any further trials should also address the gaps in evidence concerning maternal outcomes such as satisfaction with postnatal care, maternal functioning/well-being (emotional attachment, self-efficacy, competence, autonomy, confidence, self-care, coping skills) and neonatal drug adverse effects.